Jan Siberechts may have taken liberties with his painting which has misled Charlecote volunteers for years. It is possible he only sketched the house and then created the painting later and did not quite remember things. You can see on the enlargement from the painting that the house is shown with only two turrets. Some people believe that the original house was built with only two turrets but one of our most knowledgeable, but unfortunately deceased volunteers, Ted Veitch, always maintained that there were four. An American researcher, Eddy Krakhmalnikov, has unearthed the earliest representation of Charlecote in the Sheldon tapestries of Warwickshire from 1580 and it clearly shows the four turrets. So it is a bit of an open question.
This tapestry can be seen in the Market Hall Museum in Warwick.
Ref: Life on the Ground: A history of the Gardens at Charlecote Park Eddy Krakhmalnikov,